30 seconds to 2 minutes is the cross-over point for fuel consumption. Older cars take more gas to start than newer ones, so turn off your late-model cars earlier.
The trade-off is for increased tailpipe emissions. After 30 seconds to a minute the catalytic converter cools off (yes even in this weather). On restart, the car produces higher levels of NOX and CO until the converter reheats.
To summarize: turning off saves fuel but creates more smog. Idling burns more fuel, but keeps the air cleaner.
30 seconds to 2 minutes is the cross-over point for fuel consumption. Older cars take more gas to start than newer ones, so turn off your late-model cars earlier.
The trade-off is for increased tailpipe emissions. After 30 seconds to a minute the catalytic converter cools off (yes even in this weather). On restart, the car produces higher levels of NOX and CO until the converter reheats.
To summarize: turning off saves fuel but creates more smog. Idling burns more fuel, but keeps the air cleaner.
Swings and round-a-bouts really, pick yer poison
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